As a conventional fin-and-tube heat exchanger, for example, patent literature 1 discloses a heat exchanger which includes heat exchange fins, a tubular wall substantially surrounding the heat exchange fins, and a conduit extending through the heat exchange fins and the tubular wall. In the heat exchanger disclosed in patent literature 1, thermal strain occurs in the conduit because of the difference between the tubular wall and the heat exchanger. In order to reduce a thermal stress caused by the thermal strain of the conduit, the tubular wall of the heat exchanger disclosed in patent literature 1 includes groove-shaped absorbers.